1. Field of the Invention
This invention relates generally to oil lubricated bearings and more particularly to bearing assemblies having a plurality of tiltable shoes with ceramic bearing surfaces.
2. Background History
Oil lubricated bearings carrying a plurality of displaceable or tiltable shoes, the surfaces of which constitute bearing faces, have been utilized for specified applications. Limited movement of the shoes relative to a bearing housing facilitated the establishment of oil lubrication film wedges between the bearing face of each shoe and the running surface of a load which moved relative to the shoes.
An example of a thrust bearing with tiltable shoes is disclosed in commonly owned application, U.S. Ser. No. 08/360,223, filed Dec. 20, 1994 and incorporated herein by reference. Radial or journal bearings with arcuate shaped tiltable shoes arranged to facilitate the formation of oil film wedges between bearing faces and running load surfaces were disclosed in Friction Bearings, F. Findeisen, Journal TR No. 51, 9 Dec. 1975, Volume 67, Pg 5.
The employment of ceramic clad bearing faces was disclosed in German Patent DE 3,602,132 which illustrated a bearing having a base of steel, copper, or copper alloy and a ceramic bearing face containing fibers. The ceramic face was spray deposited by a cathode sputtering process. Activated lead was spray deposited to the base by a cathode sputtering process prior to spraying the ceramic layer.
The requirement for a special substrate of activated lead in German Patent DE 3,602,132 rendered the manufacture of such bearings time consuming and of considerable expense. Manufacture of the bearing was subject to potential damage or deformation of the underlying structure by tools or elevated temperatures during the formation of the ceramic layer. Further, the spray depositing of the ceramic face was a complex procedure which required specialized equipment.
A need was perceived for an improved bearing assembly which would provide the benefits associated with ceramic bearing faces at a lower cost.